LAKE COUNTY, Calif. – Lake County health officials have confirmed the first human case of West Nile virus in the county this year, at the same time as new detections of the virus have been reported in sentinel chicken flocks.
Lake County Public Health received confirmation this week of the human West Nile virus case, according to Dr. Karen Tait, the county's health officer.
Due to privacy laws, Tait could not give a lot of specifics about the case, which involve a Lake County resident.
She said the individual, who is in their 50s, contracted the infection in late July in the county. The patient recalled being at home and getting a mosquito bite.
“The patient actually recovered really well,” with no complications, said Tait.
Because West Nile virus is a reportable disease, it's part of Public Health's routine surveillance, Tait said.
The law requires that both health care providers and laboratories report the diagnosis to Public Health, she said.
“For reporting and verification purposes, clinical lab tests sometimes have false positives,” said Tait, so before they can count a case, it has to be confirmed through a public health lab.
Those public health labs usually require about a 21-day turnaround, said Tait. “That's why there is such a long lag time before we could announce it,” she said, although in a previous report on West Nile issued late in August Tait had stated that they were investigating a suspected human case.
Lake County had two human cases of West Nile virus last year and one case in 2014, according to state records.
As of Aug. 31, 123 human cases of West Nile virus had been reported in 23 of California's 58 counties, an increase from the 97 cases reported at the same time last year. Forty-six of current cases were reported in the past week, according to health officials.
Two West Nile virus-related fatalities were reported this year by Sacramento and Yolo counties.
Health officials said it only takes one bite to get West Nile virus from an infected mosquito, and anyone of any age can get this disease.
Symptoms of the mild form of West Nile virus include fever, headache, body aches, nausea vomiting, and occasionally swollen lymph glands or a skin rash. While the illness may last only a few days, some people report being sick for several weeks.
The severe form of West Nile, which occurs in less than 1 percent of cases, can affect the nervous system and can be fatal.
Tait said Public Health coordinates with the Lake County Vector Control District to do mosquito trapping in areas of concerns and additional abatement if it's warranted.
Vector Control conducts routine surveillance for West Nile virus throughout the active season. Positive detections typically occur in mosquitoes, followed by dead birds and sentinel chicken flocks.
The district reported that two sentinel chickens recently tested positive, bringing the total to four for the year. Additionally, 32 mosquito samples and three dead birds in Lake County have tested positive for West Nile virus.
“Finding West Nile virus in sentinel chickens shows that there is risk for people to get West Nile virus from the mosquitoes that are biting now,” said Jamesina Scott, Ph.D., district manager and research director.
Tait said all indications are that West Nile virus season is in full swing. “Since there is no specific treatment for the virus, the best approach is to avoid exposure to mosquito bites.”
People can become infected with West Nile virus when bitten by a mosquito after it has bitten an infected bird, the reservoir for the virus, according to Tait and Scott.
Dr. Scott explained that local West Nile virus activity often continues into September and October. “The risk of picking up West Nile virus from a mosquito bite is highest now because the mosquitoes are older – they’ve fed several times and have had more chances to pick up West Nile virus and pass it along to the next host they bite.”
She recommended that residents inspect their yards for sources of standing water where mosquitoes develop, such as ornamental ponds, wading pools and unmaintained swimming pools.
“Getting rid of standing water in your yard prevents mosquitoes from growing there and protects you, your family, and your neighbors from mosquito bites and the diseases they carry,” she said.
Scott said people want to know what the “best” repellent is. “The best repellent is the one that you will use, and there are several good choices now available as sprays, lotions, or wipes.”
The US Environmental Protection Agency has registered five different active ingredients in mosquito repellents that are proven effective: DEET, Picaridin, oil of lemon eucalyptus, IR3535, and para-menthane-diol (a synthetic version of oil of lemon eucalyptus. These five ingredients are proven to be effective and safe Scott explained.
“But they only work if you apply them,” Scott said. “And always read the label and follow the directions.”
Contracting the virus is largely preventable by taking simple, but very important precautions, such as the following, suggested by Vector Control:
– Dump or drain standing water. Mosquitoes can't begin their lives without water. If the water cannot be drained (like an unused swimming pool), call the Lake County Vector Control District at 707-263-4770 for free mosquitofish.
– Defend yourself against mosquitoes by using repellents containing DEET, Picaridin, IR3535 or oil of lemon eucalyptus. For more information about effective mosquito repellents, visit the U.S. Centers for Disease Control and Prevention at http://www.cdc.gov/westnile/faq/repellent.html .
– Avoid being outdoors when mosquitoes are present, typically dawn and dusk.
– Report neglected swimming pools by calling 707-263-4770 or visiting www.lcvcd.org . Anonymous calls are accepted. Just one neglected pool can produce more than one million mosquitoes and affect people up to five miles away.
Residents can contact the Lake County Vector Control District at 707-263-4770 from 7:30 a.m. to 4 p.m., Monday through Friday, or online at www.LCVCD.org to request help for mosquito problems, report neglected pools and other mosquito sources, or for information about mosquitoes, ticks, and other vectors and the disease they transmit.
Email Elizabeth Larson at This email address is being protected from spambots. You need JavaScript enabled to view it. . Follow her on Twitter, @ERLarson, or Lake County News, @LakeCoNews.